The fact that output characteristics of an engine such as a gasoline engine change according to the state of the intake and exhaust is well known. Changing the timing and lift amount of the intake and exhaust valves according to the driving state of the vehicle in order to improve fuel efficiency or increase the torque in the low to mid speed range and the like is common practice. Control of the valve timing and lift amount has been done by various mechanisms for changing the cam phase with respect to the crank angle, or changing the cam itself, which drives the valves, or the like. Recently, however, a mechanism has been proposed for driving the valves using electromagnetic force in order to further improve the degree of freedom of control, as disclosed in Japanese Patent Laid-Open Publication No. 11-11778. Further, a valve mechanism for controlling valve opening and closing using hydraulic pressure (fluid pressure) is disclosed in Japanese Patent Laid-Open Publication No. 8-189315.
The control device disclosed in Japanese Patent Laid-Open Publication No. 11-11778, mentioned above, adjusts the braking force during deceleration such that smooth deceleration is achieved by adjusting negative torque generated by the engine in each cylinder. The negative torque is adjusted by shortening the opening time of either the intake valve or the exhaust valve during deceleration. That is, the control device finely controls the positive and negative torque of the engine by controlling the torque of each cylinder, and complements the control of the driving torque from the transmission.
However, positive or negative torque generated by the engine greatly affects the torque applied to the transmission. As a result, the shift characteristics of the transmission change depending on the torque generated by the engine. In spite of this engine torque control during shifting of the transmission is mainly performed by control to retard the ignition timing. In addition, the aforementioned publication goes only as far as to consider temporarily reducing engine torque by fuel cut control and throttle control. Engine torque control during shifting using the kind of electromagnetically driven valves disclosed in the aforementioned publication is not specifically considered.
Therefore, a preferable mode of control (a mode for so-called harmonized control) for controlling shifting in a transmission and controlling the engine torque using electromagnetically driven valves has not been known. Accordingly, there is still room for development regarding torque control of an engine having electromagnetically driven valves.